High-speed/high-pressure rotary pump



March 24, 1970 H. R. VOIGT HIGH-SPEED/HIGH-PRESSURE ROTARY PUMP 4 Sheets-Sheet 1 Filed Aug. 2, 1968 R m N E V e w M u f A'OWL 5e, z/voaae MAETE/VS A TTOENE/S'.

March 24, 1970 H. R. VOIGT 3,502,031

HIGH-SPEED/HIGHPRESSURE ROTARY PUMP Filed Aug. 2, 1968 4 Sheets-Sheet 2 INVENTOR. #ELLMUT 1?. 1/0/67 FOWLE'E, KNOBBE MAE revs March 24, 1970 H. R. VOIGT HIGH-SPEED/HIGH-PRESSURE ROTARY PUMP 4 Sheets-Sheet 4 Filed Aug. 2. 1968 INVENTOR. HELAMA/T E VO/GT 5 y M M w 2 N5 0 5w 5 7 4 MM WM W United States Patent 3,502,031 HIGH-SPEED/HIGH-PRESSURE ROTARY PUMP 'Hellmut R. Voigt, 11821 Redbank St.,

Sun Valley, Calif. 91352 Filed Aug. 2, 1968, Sci. No. 749,825 Int. 'Cl. F04c N00 US. Cl. 103123 11 Claims ABSTRACT OF THE DISCLOSURE Three disk-like rotors on a shaft are formed with an arcuate recess in each axial face which varies in depth from a maximum to zero at a flat land that moves in close clearance with adjacent fixed structure to form a chamber. Two sliders reciprocate axially within the fixed structure between the rotors with the slider ends fitting in sealing relation within the adjacent Working chambers. The sliders divide the chambers into suction and pressure compartments which vary in volume as the rotors rotate to provide pumping action through fluid inlet and outlet ports opening into the chambers on opposite sides of the sliders.

BACKGROUND OF THE INVENTION This invention relates to high speed rotary machines which are particularly adapted to operate as positive displacement, high pressure rotary pumps or compressors. More specifically, the invention relates to that type of machine having a plurality of rotors defining arcuate chambers in combination with adjacent fixed structure, with the rotors being divided into suction and pressure compartments by slider assemblies or abutments which slide within the chambers and reciprocate axially in the stationary structure between the rotors.

This type of machine provides several advantages over more conventional machines of the type having reciprocating pistons or rotating vanes in that the only reciprocating parts are the relatively small light weight slider assemblies, as contrasted with heavy pistons and connecting rods, and the rotating parts do not have a shifting center of gravity as do machines with speed limiting, rotating flexible vanes. Although machines of this general type have been known for many years, they have never become widely accepted. It is believed that one of the reasons for this is that the prior art machines have not been adequately balanced from both a weight and fluid pressure standpoint. This in turn has reduced the speed at which such machines could be satisfactorily operated and also adversely affects the power-to-weight and power-tosize ratios. The lack of complete balancing also introduces additional wear and hence shortens the life of the apparatus.

SUMMARY OF THE INVENTION A high-speed, high-pressure rotary machine of the present invention is formed by fixed housing structure defining three axially spaced annular cavities, with the fixed structure including stators separating the cavities. Three rotors mounted on a shaft and positioned within a respective one of the cavities are formed with an arcuate recess in each axial face. These recesses in combination with the adjacent fixed surfaces form arcuate chambers. The axial depth of each chamber smoothly varies from a maximum to zero at a flat land area, with the land being in close clearance with the adjacent fixed structure. The arcuate chambers on opposite faces of a rotor are 180 offset and the chambers on opposite ends of the stators are 180 offset. This arrangement provides proper weight balancing and also proper balancing of the fluid forces. A slider assembly is mounted for axial reciprocation in each of the stators, 180 offset from each other. The

3,502,031 Patented Mar. 24, 1970 ends of the slider assemblies extend into the adjacent working chambers and fit in sealing relation within the working chambers to divide each chamber into a suction compartment and a pressure compartment. As the rotors rotate, the slider assemblies are axially reciprocated by the slope of the axial rotor walls of the chambers, thus varying the volume of the compartments and causing fluid flow through inlet and outlet ports formed in the stators and opening into adjacent chambers on opposite sides of the ends of the slider assemblies.

The structure of the type described can be operated at very high rotational speeds in view of excellent hydraulic balancing and in view of the low mass of the slider assemblies, the only components which change direction during operation. Another advantage of the arrangement is that additional stator and rotor units may be added as desired to increase the capacity of the machine.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing the exterior of a pump made in accordance with the invention;

FIG. 2 is an exploded perspective view of the pump of FIG. 1 arranged in two columns;

FIG. 3 is a cross-sectional view of the pump along the lines 33 of FIG. 1;

FIG. 4 is a cross-sectional View of the pump on line 4-4 of FIG. 3 illustrating a fluid inlet and outlet and a slider assembly;

FIG. 5 is a cross-sectional view on the line 55 of FIG. 4 further illustrating the inlet and outlet and the slider assembly;

FIG. 6 is a 360 developmental view, which is partially schematic, illustrating the operation of the pump and the slider assemblies;

FIG. 7 is a cross-sectional view of a portion of a pump of the type shown in FIGS. 16 showing a reed valve positioned in the fluid outlet; and

FIG. 8 is an axial view of the valve of FIG. 7 and the adjacent structure.

DETAIL-ED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION The machine illustrated in the drawings will generally be referred to as a pump throughout the description although it should be understood initially that the machine may also serve as a compressor; and if pressurized fluid is applied to the machine it can serve as a motor or prime mover.

Referring to FIG. 1, the pump of the invention may be seen as having a generally cubic shape with fixed housing structure formed by a front cover 10, a front stator or housing section 12, an end stator or housing section 14 and a rear cover 16. These elements are sandwiched together in axial relationship by a plurality of bolts 17 extending through the corners of the stationary elements, and threaded fasteners 18.

As seen in greater detail in FIGS. 2 and 3, the front cover 10 and the rear cover 16 include cylindrical portions of reduced diameter which slip fit with the stators 12 and 14; and in cooperation with the stators, they define annular spaces for receiving O-rings 19 and 20. Similarly the adjacent ends of the stators 12 and 14 are slip fit together and sealed by an O-ring 21.

Within the pump, the front cover 10 is spaced from the stator 12 to define an annular cavity 22, FIG. 2, formed by the cover 10 and the stator 12. Similarly, annular cavities 23 and 24 of the same size are formed respectively between the stators 12 and 14 and between the stator 14 and the end cover 16. Extending through an opening in the front cover 10 is a drive shaft 26 carrying a front, disklike rotor 28 positioned in the cavity 22, a central rotor 30 positioned within the cavity 23, and an end rotor 32 positioned within the cavity 24. The rotors include axially elongated hubs 28a, 30a, and 32a supporting axially thin disk portions 28b, 30b, and 32b. The rotors are rotationally secured to the shaft 26 by an axially extending key 34 positioned within a mating slot 35 in the shaft 26 and similar slots 35a formed within the rotor hubs. The considerable axial length of the rotors insures rigid connections to the shaft, which is important in maintaining close clearances between the rotor disk portions and the stationary structure. A retainer screw 36 threaded into the end of the shaft 26 axially retains the rotors on the shaft. The screw is turned via a hexagonal socket 36a formed in the screw head.

Referring to FIG. 3, the shaft 26 is joined to the housing structure by a generally tubular shaft seal 38 which is press fit into the hub 10a of the front cover 10. A short compression spring 40 rests on an internal shoulder 38a of the shaft seal 38' and urges a bearing support sleeve 42 inwardly. An O-ring 39 resting on a second internal shoulder 38b, extends between the seal 38 and the sleeve 42 to seal the front end of the pump. The sleeve 42 supports a ring bearing 44 having an axially extending bearing surface urged against the hub 28a of the rotor 28 by the spring 40. (To simplify FIG. 2, the bearings and seals described in this paragraph are not shown in FIG. 2.)

An O-ring 46 positioned within an annular groove in shaft 26 seals the joint between the rotor 28 and the shaft. A pair of sleeve bearings 48 and 49 are respectively press fit into the stators 12 and 14, with the front sleeve bearing 48 surrounding a rearwardly extending axial extension of the hub 28a of the rotor 28 and the forward extension of the hub 30a of the rotor 30, while the rear sleeve bearing 49 surrounds the rear axial extension of the hub 30:: and the forwardly extending axial extension of the hub 32a of the rotor 32. The clearances between the rotating components and the fixed structure are quite small so that good seals between the adjacent surfaces are obtained.

Referring to FIGS. 2 and 3, the front rotor 28 has formed in the opposite axial faces of its disk portion 30b a pair of arcuately extending recesses which form arcuate chambers 29a and 29b in combination with the adjacent cover 10 and stator 12. The thin common axial wall 28d of the chambers 29a and 29b smoothly varies in its axial position from one rotor face to the other face. As may be seen from FIG. 6, the position or curvature of the wall 28d varies in a symmetrical fashion and preferably has the shape of a sinusoidal curve extending from one edge of a dam or land 28e, through the arcuate chamber 29a to the other edge of the land 28e, which in the arrangement shown in approximately 330. Thus, the arcuate length of the land 282 is approximately 30. Referring to FIGS. 2 and 5, the land 28e is positioned adjacent the front cover 10.

The chamber 29b is identical to the chamber 29a to the extent that its ends are separated by a flat land 28f, which is partially seen in FIG. adjacent the front stator 12. The land 28 is identical to the land 28c; however, it is 180 offset from the land 28e. The axial depth of the chambers 29a and 29b varies from a maximum at the arcuate midpoints to zero where they terminate at the lands 28e and 28]. It will be seen that the radially inner walls of the chambers 29a and 29b are spaced from the outer surface of the hub 28a, and the outer walls of the chambers define an outer rim 28g.

Referring to FIGS. 2, 3, and 5, the central rotor 30 is similarly formed in the opposite axial faces with a pair of arcuate recesses that in combination with the adjacent surfaces of the stators l2 and 14 define a pair of chambers 31a and 31b. Their chambers have a common, thin axial wall 30d and their ends are defined by a pair of lands 3% and 30f. The radially outer wall of the chambers 31a and 31b define a rim 30g and the radially inner walls are spaced from the hub 30a. The chamber 31a is 180 arcuately offset from the chambers 31b and 29b. Similarly, arcuate recesses in the rear rotor 32 together with the adjacent surfaces of the stator 14 and the rear cover 16 define a pair of arcuate chambers 33a and 33b.

As seen in FIG. 2, the rotor 30 is formed with a shallow groove 30/1 in the surface of the land 30c. This groove is not radially aligned and it extends beyond the radial width of the chamber 31a, with one end of the groove terminating at the hub 30a spaced slightly from one end of the chamber 31a and the other end of the groove terminating at the outer periphery of the rotor spaced slightly from the other end of the chamber. A similar groove 3211 is formed in the face of the land 32a of the rotor 32. Such grooves (not shown) are also formed in the land 30], FIG. 5, of the rotor 30 and in the land 28] of the rotor 28, but none are formed in the lands 28a and 32].

Referring to FIGS. 2 and 4, it may be seen that the housing or stator 12 is formed with an axially extending opening 52 having an arcuate cross section which is offset from the center, axially aligned with the chambers 29b and 31a in the adjacent rotors 28 and 30 and opens into the cavities 22 and 23. A pair of arcuately spaced, axially extending plates 54 divide the opening 52 into a central hole 56 and a pair of passages 57 and 58 on opposite sides of the hole 56. Note that the plates 54 are radially aligned also so that the hole 56 forms an arcuate sector with a somewhat frusto conical shape.

Positioned within the hole 56 is a slider assembly 60 comprising two axially aligned slider units 62 and 64 separated by an O-ring 66. The slider units 62 and 64 are formed by a plurality of vanes 68 which are chamfered at their axially outer ends to define small grooves or chambers 69 between the adjacent outer ends, which in operation act as labyrinth seals. These outer ends of the vanes forming the slider units 62 and 64 are dimensioned to fit snugly within the arcuate working chambers 29]) and 31a which are adjacent to the stator 12. The cross section of the slider units 62 and 64 mates with the cross section of the hole 56 so that the slider assembly is axially movable in the hole 56. The inner ends of the slider units 62 and 64 are separated by the O-ring 66 which conforms to the shape of the hole 56, as may be seen from FIG. 4. Note that since the working chamber 2% is angularly offset 180 with the working chamber 31a in the rotor 30, the axial distance between the axial walls 28d and 30d is constant so that the relatively constant length of the slider assembly 60 may be accommodated. However, the O- ring 66 is compressed somewhat so that the ends of the slider unit 62 and 64 make positive contact at all times with the walls 28d and 30d, also the O-ring compensates for slight tolerance variations and wear on the ends of the slider vanes 68'.

As may be seen from FIGS. 5 and 6, the slider unit 62 in combination with the land 28 divides the working chamber 29b into a suction compartment 29c and a pressure compartment 29d. Similarly, the arcuate working chamber 31a is separated into a suction compartment 310 and a pressure compartment 31d by the slider unit 64 and the land 30c.

Referring now to FIGS. 2, 4, 5 and 6, it can be seen that the passage 57 forms a fluid inlet port with one end in communication with the suction compartment 290 of the chamber 29b and with the other end in communication with a suction compartment 310 of the chamber 31a. The inlet port 57 is intersected by an inlet bore 70 extending transversely in the stator 12 to the exterior of the stator and having an inlet fitting 71 threaded into the bore with a suitable O-ring sealing the joint.

In similar fashion, the passage 58 on the other side of slider receiving hole 56 forms an outlet port with one end in communication with the pressure compartment 29d of the chamber 29b and the other end in communication with the pressure compartment 31d of the chamber 31a. The outlet port 58 is intersected by a bore 73 extending transversely in the stator 12 to the exterior of the housing. An outlet fitting 74 is threaded into the bore and an O-ring 75 seals the joint between the fitting and the stator. Diametrically opposed from the opening 52 is a space 76 in the stator 12, as may be seen from FIGS. 1-4, which reduces the weight of the pump. This space 76 may be left open or it may be covered by a suitable plate 76a and conveniently used for storing spare slider units 60.

As may be seen from FIGS. 2 and 6, the stator 14 is formed in a manner similar to the stator 12 but angularly offset with respect to stator 12 byv 180. Thus, an axially extending opening 80- formed in the stator 14 is divided by a pair of plates 81 to form a central hole 82 and a pair of passages 83 and 84 on opposite sides of the central hole 82. A slider assembly 85 comprising slider units 86 and 87 and an O-ring 88 is mounted in the central hole 80 With its outer ends positioned in sliding relation with the working chambers 31b and 33a formed in the adjacent surfaces of the rotors 30 and 32. The slider assembly 85 in combination with the lands 30 and 32a formed respectively on the rotors 30 and 32 divide the chambers 31b and 33a into suction compartments 31c and 330 and pressure compartments 31 and 33a.

The passage 83 forms a fluid inlet port in the stator 14 with one end in communication with the suction compartment Me and the other end in communication with the suction compartment 33c. A bore 89, FIG. 6, intersects the inlet ports 83 and threadably receives an inlet fitting 90, FIGS. 1, 2 and 5, with an O-ring 90a, FIG. 5, sandwiched between the fitting flange and the stator 14. In similar fashion, the passage 84, FIGS. 2 and 6, forms a fluid outlet port with one end in communication with the pressure compartment 31 and the other end in communication with the pressure compartment 3301. The outlet port is intersected by a bore 91, FIG. 6, in the stator 14 which threadably receives an outlet fitting 92, FIGS. 1, 2 and 5, with an O-ring 92a, FIG. 5, between the fitting flange and the stator.

As may be seen in FIG. 5, the side of the stator 14 which is diametrically opposite from the slider assembly 85 is formed with a space 93, comparable to space 76 in the stator 12, the space may be enclosed by a cover 93a.

OPERATION The pump shaft 26 may be rotated in either direction, but to be consistent with the terminology given to the inlet and outlet ports in the foregoing description, assume that the shaft and the rotors are rotated as indicated by the arrows in FIG. 6, which is in a clockwise direction as viewed in FIG. 4. This direction is counterclockwise as viewed from the front end of the pump in FIGS. 1 and 2. With this rotation, the suction compartments 29c, 31c, 31c and 330, FIG. 6, increase in volume as the sinusoidal axial walls of the working chambers in the rotors slide past the ends of the slider assemblies; and as a result, fluid is drawn into these compartments through the inlet fittings 71 and 90 and inlet ports 57 and 83. Simultaneously, the volume of the pressure compartments 29d, 31d, 31 and 33d is decreased so that the fluid in these compartments is being compressed or pressurized, with the result that fluid is forced outwardly through the outlet ports 58 and 84 and through the outlet fittings 74 and 92.

Since the chamber 29b and the chamber 31a are 180 offset and the chambers 31b and 3311 are similarly arranged, the result is a smooth continuous output. Also, the fluid forces are effectively balanced so that hearing loads are minimized.

It is important from an efliciency and pressure standpoint that good seals be created by the slider assemblies and the rotor lands in forming the pressure and suction compartments. The quality of the seal formed by the ends of the slider assemblies is enhanced by the use of separate vanes 68 forming the small grooves 69, in that each vane acts like a separate seal, thus overall forming a labyrinth seal. Also the grooves 30h and 3211 in the rotor lands interrupt the land surface to form two separate seals. The angled orientation of the grooves 30/2 and 32h facilitate the smoothness of the movement of the lands passed the slider ends.

As the axial rotor surfaces of the working chambers are moved past the ends of the slider assemblies, the slider assemblies are cammed to reciprocate axially within their holes. Due to the shallowness of the chambers and the relatively small mass of the slider assemblies, the rotors may be rotated at extremely high speeds. This, in turn, enables the pump to provide relatively high pressures and further enables it to operate as a compressor if desired. Another feature of the pump is the light-weight construction of the rotors which gives a high power-toweight ratio. The rotors are nevertheless quite strong in view of the outer annular rim which lends rigidity to the structure and strengthens the thin annular portion of the rotors forming the axial working chamber walls. Moreover, since the dynamic fluid forces produced by the pump during operation are completely balanced, the rotors do not need to be exceptionally strong.

The rims 28g, 30g and 32g formed on the rotors also improve the effectiveness of the seal between the rotors and the adjacent stationary structure in that these rims provide axial surfaces as Well as outer circumferential surfaces which slide in engagement with the adjacent structure. This in turn contributes to the high pressures which may be attained by the pump.

Also adding to the excellence of the pump is the fact that the rotors are weight balanced as well as hydraulically or dynamically balanced in view of the fact that the chambers are formed in both axial faces of each rotor, it being understood that the outer arcuate chambers 29a and 3311 are not working chambers utilized for pumping action. Nevertheless what pressures do develop in those outer chambers shuold be balanced between opposite ends of the pump.

Although the pump may be formed with components of various dimensions depending upon the task to be performed and the capacities desired, it may he helpful to obtain an understanding of the invention if preferred dimensions of an operating unit are given. Overall, the pump is extremely compact for its power-to-weight ratio and power-to-size ratio when compared with other pumps. Of particular significance are the dimensions of the rotors. In a working embodiment, the overall axial thickness of the rotor disks, i.e. not counting the hubs, is approximately .200 inch with the common axial chamber wall being approximately .100 inch and the axial depth of each arcuate chamber varying from a maximum of .100 inch to zero. As mentioned, the arcuate chambers extend for approximately 330 with the lands extending for approximately 30. The radial dimension of the arcuate chambers and the mating slider assemblies is approximately .375 inch.

Notwithstanding the continuous high velocity and flow of fluid through the pump, it may be necessary to utilize check valves in the pump outlets when a predetermined extreme high pressure differential exists between the inlet and outlet. This is particularly important when compressible fluids are involved. To this end, there is shown in FIGS. 7 and 8 a pair of flexible reed valves 96a and b extending across the ends of an outlet port 97. The reeds are clamped to the surrounding stator 98 valve seats 99 and valve stops 104 by suitable fasteners 100. The valve stops 104 are more rigid than the thin reed valves 96 so that they limit the opening movement of the valves. The stops 104, the valves 96a and 96b and the valve seats 99 are positioned within the recesses surrounding the ends of the port 97 so that the sides of the seats 99 facing the rotors are flush with the stator 98. The seats 99 completely surround the ends of the port 97, and the seats may be bonded to the stator recesses in the areas spaced from the fasteners to insure that the seats are not moved by back pressure.

The valve 96a is shown in a full open position in view of the fact that fluid is being forced out of its adjacent pressure compartment 105. The stop 104 prevents further opening movement of the valve 96a. The valve 96b is shown in a partially open position, spaced from its seat 99 and its stop 104, since the pressure compartment 106 is at that instant quite small and hence output is slight. It will be understood that when the ends of a slider assembly 101 engage the flat land portions of the rotors 102 and 103 the pressurizing action in the adjacent chamber will cease for an instant so that the valves will automatically return to their normally closed positions engaging the valve seats 99 due to their inherent flexibility and also due to the back pressure which exists in the outlet. When one valve is closed, the other is, of course, fully open.

It should also be understood that when the slider assembly is engaging a land area, the pump inlet is in direct communication 'with an outlet if the valves are not provided. As soon as the rotors 102 and 103 are rotated a slight amount further so that the slider assembly is no longer on a land area, the pressurizing action in that chamber commences again so that the valves are once more opened when back pressure is overcome.

What is claimed is:

1. A high-speed high-pressure rotary machine comprismg:

fixed housing structure defining three axially spaced annular cavities, the fixed structure including annular stators separating the cavities;

three rotors mounted on a shaft and positioned within a respective one of said cavities, each of said rotors having an arcuate recess formed in each axial face which in combination with the adjacent fixed surfaces forms an arcuate chamber, the axial depth of each chamber smoothly varying from a maximum to zero at a flat land, the land being in sliding contact with the adjacent fixed structure, the arcuate chambers in opposite faces of a rotor being 180 out of alignment and the arcuate chambers facing opposite ends of said stators being 180 out of alignment;

means defining an axially extending hole formed in each of said stators and opening into the adjacent chambers, the hole in one stator being 180 offset from the hole in the other stator;

a slider assembly slidably mounted Within each of said holes with the ends of said slider assemblies fitting in sealing relation within the adjacent rotor chambers to divide each of said adjacent chambers into a suction compartment and a pressure compartment which vary in volume as the rotors rotate with the slider assemblies being axially reciprocated within said holes; and

means in said stators defining fluid inlet and fluid outlet ports opening into said adjacent chambers on opposite sides of the ends of the slider assemblies.

2. The machine of claim 1 wherein the axial surface of each of said rotors forming said arcuate recesses varies in its axial position in the form of a sinusoidal curve with the maximum depth of the recesses corresponding to the peak of the sinusoidal curve and said land forming the ends of said curve.

3. The machine of claim 1 wherein:

said stators include mating cylindrical portions about their inner axial faces which join together to form the outer cylindrical wall of the cavity between said stators; and

said fixed housing structure further includes a pair of end covers which cooperate with the outer axial faces of said stators to define the outer two of said three annular cavities.

4. The machine of claim 3 wherein:

said stators and said covers have a generally rectangular shaped cross section; and

including a plurality of bolts extending through the corners of the stators and the covers to clamp the rotors and covers together as a fixed unit.

5. The machine of claim 1 wherein said slider assembly includes a pair of sliding units axially separated by a resilient element to assist in obtaining a good seal between the ends of the slider units and the arcuate recesses and to compensate for wear of the components.

6. A high-speed high-pressure rotary machine comprising:

fixed housing structure defining a pair of axially spaced annular cavities separated by a stator;

a shaft extending into the housing structure and through said stator;

a pair of rotors mounted on said shaft and positioned within a respective one of said cavities, each of said rotors including a central hub supporting a thin disk having an arcuate recess formed in each axial face of the rotor with a short cylindrical rim forming the radially outer arcuate wall of said recesses, and the outer surface of said hub being spaced from the radially inner wall of said recesses, the axial surface of the rotor surrounding the recesses being positioned in close clearance with the surrounding fixed structure to form arcuate chambers in combination with the recesses, the depth of each chamber smoothly varying from a maximum to zero at a flat land which is positioned in close clearance with the adjacent fixed structure, the arcuate chambers in opposite faces of each rotor being offset; means defining an axially extending hole formed in said stator and opening into the adjacent chambers;

a slider assembly slidably mounted within said hole with the ends of the slider assemblies fitting in sealing relation within the opposing chambers to divide the chambers into a suction compartment and a pressure compartment, the slider assembly being axially reciprocated within the hole as the rotors are rotated; and

means in said stator defining a fluid inlet port and a fluid outlet port both opening into the adjacent chambers on opposite sides of the slider assembly hole.

7. The machine of claim 6 wherein said cavities have an axial dimension of approximately .200 inch and said arcuate chambers have a maximum depth of approximatel .100 inch.

8. The machine of claim 6 wherein the maximum depth of said chambers is approximately .100 inch and the chambers extend circumferentially approximately 330 while the lands extend approximately 30.

9. The machine of claim 6 wherein the means defining said hole and said inlet and outlet ports includes a single opening extending axially through the rotor and extending circumferentially in radial alignment with said recess, the opening being divided by a pair of arcuately spaced, axially and radicall extending plates into the central hole for receiving the slider assembly, the fluid inlet port on one side of the hole and the fluid outlet port on the other side of the hole, the inlet and outlet ports being further connected to fittings extending outwardly through the stator.

10. The machine of claim 6 including means defining an elongated slot in the axial face of said land improving its sealing ability, the slot extending beyond the radial width of said arcuate chambers but being angularly aligned with respect to a radial line with one end of the slot closely spaced from one end of the arcuate chamber and the other end of the slot closely spaced from the other end of the arcuate chamber.

11. The machine of claim 6 including a pair of lightweight reed check valves positioned within said stator across the opposite end of the outlet port to control the flow of fluid out of the pressure chambers and to prevent reverse flow through the outlet port into the pressure compartments.

(References on following page) References Cited UNITED STATES PATENTS 2,925,779 2/1960 Pelladeau 103-123 FOREIGN PATENTS Ernst 91-96 h p 103 123 639,541 12/1936 Germany.

Saxdn 12314 5 Lickfeldt 123 14 DONLEY J. STOCKING, Prlmary Examlner Deubel 1 3 123 W.J.GOODLIN,AssistantExaminer 

